Circuit interrupter



March 14, 1939. w. M. sec-r1. JR

' CIRCUIT INTERRUPTER Filed July 1, 1957 s Sheets-Sheet 1 a 5 oo oo 0o 00 l. 5

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INVENTOR. 9H4 an Mk BY M 1(- 898 A TTORNEY March 14, 1939. w. M; sco-rT, JR- 2,150,566

CIRCUIT INTERRUPTER Filed July 1, 1937 3 Sheets-Sheet 2 I I v ATTORNEY,

F1475 BY gwggbw March 14, 1939. w. M. SCOTT. JR

CIRCUIT INTERRUPTER Filed July 1, 1957' 5 Sheets-Sheet 3 INSULJTION INVENTOR.

ATTORNEY Patented Mar. 14, 1939 CIRCUIT INTERRUPTER- William M. Scott, Jr., Bryn Mawr, Pa., assignor .to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of New Jersey Application July 1, 1937, Serial No. 151,359

ail Claims.

My invention relates to electrical circuit interrupters, or automatic circuit breakers, more particularly to new and improved contact structures and operating means therefor, and has for an.

object the provision of a simple, rugged and reliable circuit breaker of high current carrying and rupturing capacities.

The time constants of electrical circuits are frequently such that the rate of rise of current may be of the order of 10,000,000 amperes per second though the current because of other limitations would not in one second reach the indicated maximum value. In terms of operation of typical circuit breakers of the prior art whose opening times are of the order of one-tenth of a second, the current may, before suflicient arc resistanceis introduced adequately to limit its rise, reach a value of the order of 250,000 amperes, which is above and beyond those current values ordinary circuits and apparatus are designed to withstand. Thus for the aforesaid value of current the reaction of the magnetic iiux, incident to current flow, may produce on a conductor a force of the order and upwardly of one ton per linear foot acting in a direction normal to the axis of the conductor. The heat produced, since increasing as the square of the current, is also very great. In consequence, it is highly advantageous to provide a circuit breaker which will function to limit both the maximum value of abnormal or overload current and the length of time such abnormal current flows, in order to provide adequate protection for the associated electrical circuits and the apparatus included therein.

In carrying out my invention, in one form thereof, I provide an actuating mechanism, and particularly including those parts which are antomatically moved from a closed to an open circuit position, of minimum mass. More particularly, a bridging member preferably comprises a plurality of relatively thin, plate-like elements, laterally spaced one from the other for ventilation purposes. By means of an actuatin-g member connected to the bridging member intermediate its ends, the latter may be moved into and out of a circuitclosing position. In the closed position, opposite ends of the bridging member are biased into edgewise engagement with stationary contact structures; made massive so that the heat generation and temperature rise will be very low, and lower than that of the bridging member. Accordingly there occurs a flow of heat from the bridging member to those structures, which is facilitated by thickened end portions of each bridging element. Ventilation through the vertical spaces between the elements further aids in maintaining their temperature within safe limits though their mass has been materially reduced.

To increase the opening speed, a heavy, powerful spring acting through a short distance, produces an exceedingly high rate of acceleration of the moving parts, a spring of lesser strength remaining effective during the entire opening movement of the circuit breaker.

Inaccord with a further aspect thereof, my invention is particularly characterized by movement of the bridging member to the closed circuit position so that the contact surfaces at one end thereof first make abutting contact engagement with one of the stationary structures; the surfaces at the other end, disposed at an angle to those at the one end and generally tangential to a line connecting said spaced surfaces, are thenslid along and in wiping contact engagement with the other contact structure to develop circuit closing pressures between all of the.con- 'tactsurfaces of the bridging member and of the structures.

In accord with another aspect of my invention, the bridging member, operated by means of a pivotal connection located intermediate its ends, is in such a relation to the stationary contact structures that magnetic forces on opposite sides of the pivotal connection do not tend to separate the contacts as long as that connection is restrained in a fixed position. Upon release thereof, the magnetic forces act in directions to produce increased acceleration of the bridging member to its open circuit position.

My invention further includes features of construction, combination and arrangement hereinafter described and claimed.

For a more complete understanding of my invention, reference should now be had to the drawings wherein:

Figure 1 is a diagrammatic view of a circuit breaker embodying my invention;

Fig. 2 is an elevation partly in section of a circuit breaker with certain of the parts omitted;

Fig. 3 is a vertical elevation, partly in section, of the assembly of bridging elements of Fig. 2, as viewed from the right and toward the upper contact surfaces;

Fig. 4 is a sectional elevation taken along the line 4-4 of Fig. 3;

Fig. 5 is a sectional elevation taken along the line 5 of Fig. 2;

Fig. 6 is an enlarged sectional elevation of a portion of a bridging element and coupling pin,

in general like, but differing in part, from those shown in Fig. 5;

Fig. 7 is an end elevation, taken along the line I of Fig. 2, of the spring housing and spider;

Fig. 8 is a perspective view 01 the arresting means or abutment block shown in Fig. 2;

Fig. 9 is a detail 01' the bufler plunger and associated springs of Fig. 2;

Fig.'10 is a fractional elevation showing an elongated opening provided in a bushing of the bridging member of Fig. 2;

Fig. 11 is a fractional elevation oi! one of the adjusting bolts for the abutment block of Figs. 2 and 8;

Fig. 12 is an elevation partly in section of a modified form of a circuit breaker with certain parts omitted;

Fig. 13 is a sectional elevation of the circuit breaker of Fig. 12 taken on the line I3--I3 with certain parts omitted; and

Fig. 14 is a perspective view of a link or arresting means of the circuit breaker of Figs. 12 and 13.

Referring to the drawings, I have shown my invention in one form as applied to a circuit breaker whose stationary contact structures I0 and II are connected respectively to studs or connectors I2 and I3 by means of bus bar assemblies I2a and I 3a. A bridging member I4 is mounted for movement into and out of engagement with the stationary contact structures In and II of massive construction to provide high current-carrying and heat-absorbing capacities. The bridging member I4 preferably comprises a plurality of substantially duplicate, fiat, platelike bridging elements which are relatively thin and wide to provide a maximum radiating surface for the dissipation of heat and a maximum strength for their weight and which, by means of a pivot pin I5 intermediate the ends thereof, are movable into and out of edgewise engagement with the stationary contactstructures I0 and I I. It is to be understood the number of bridging elements may be varied as desired to provide the necessary current-carrying capacity for each pole or circuit of the circuit breaker, only a single pole of the breaker being shown.

In the illustrated form of my invention I have shown the bridging member I4 as comprising four bridging elements I6, i1, I8 and I9, Fig. 3, each provided at its upper end with a vertically disposed contact surface or insert Ha, preferably of silver, which cooperates with corresponding surfaces or inserts llia of the stationary structure Ill. The lower ends of elements I6-I9 are provided with horizontally disposed silver inserts Mb which engage corresponding horizontally dis posed contact surfaces or inserts III) of structure II. Since the bridging elements are preferably formed of copper, I prefer to provide bushings Hid-49a of hardened steel to receive the pin I5. Each bushing is pressed within openings intermediate the ends of its associated element with elongated openings of the bushings in vertical alignment as shown in Fig. 10.

The bridging member I 4 is maintained in its closed circuit position by means of an actuating member 20 itself rigidly restrained in a closed circuit position, against the bias of one or more pairs of opening springs 22 and 23 each encircling a rod 24, by means of a releasable restraining means, a plurality of forms of which are well known to those skilled in this art and which are characterizedby their quick and speedy release of the movable contact member; For simplicity, I have shown the rigid restraining means in the form of a simple latching member 2i pivoted at Zia and arranged to engage a hook-shaped end 20a of member 20. The actuating member 20 and the rod 24 are each connected to the pin II intermediate its ends and additionally serve as guides and supports for the bridging member ll which, it will be observed, is semi-floating or bodily movable. As shown, the actuating member 20 is of rectangular cross-section while the rod 24 is an integral, cylindrical, extension thereof. By making the rod 24 and member 20 in one piece, additional guides or bearings are not needed.

The actuating member 20 and the pin I5, as viewed in Figs. 1 and 2, are moved to the left by the springs 22 and 23 during circuit opening movement, and by suitable operating mechanism to the right during closure of the circuit breaker. The elements I6-I9 are disposed in planes normal to the planes of contact surfaces Ilia and Na for edgewise engagement therewith to the end that the stresses shall be applied to the elements in directions normal to their greatest dimensions; or towards the portions of adequate or maximum strength. v

In the closed position the lower end of the bridging member is spaced 9. short distance from an arresting means or abutment block 25 provided with a concave bearing surface comple mentary to convex portions extending from elements Iii-I9 and together comprising a bearing surface indicated at 2?. ized contact pressure is maintained upon both the vertical contact surfaces Illa, Ma and the horizontal surfaces Ill), Mb, by means of one or more springs 28 operatively connected to the elements I6-I9 and the abutment 25. The line oi action of the springs 28 is such that the vertical component, effective on the lower surfaces, is substantially equal to the effect of the horizontal component in producing circuit-closing pressure at the upper surfaces.

Any wear occurring at the contact surfaces I lb and I do is compensated for by downward movement of the bridging member, the vertically elongated openings, Fig. 10, provided in bushings IBo-ISa permitting this adjustment to take place automatically. Wear of the vertical surfaces Ilia, I ia has the effect of decreasing the clearance or spacing between complementary surfaces 25a and 21. As long as there is clearance the contact pressures remain at suitably high values. later explained in connection with Fig. 2, the contact structure It] may be adjusted to compensate for the wear and to predeterminc the clearance between surfaces 25a and 27.

For certain applications it is sometimes desirable to trip the circuit breaker to its open position only in response to reverse current, while the current flowing in the normal direction may, due to surges or due to sudden application of high momentary loads, rise to very high values. The forces due to the reaction between the magnetic fluxes produced by such currents, have in the past forced or blown the contacts apart to the detriment of their conducting surfaces.

In accord with my invention, however, it is to be observed the conductor or bus .bar assemblies lZa and l3a. in conjunction with the circuit breaker contact structures I2, i3 and I4, form a current path 01' U-shape with bridging Substantial and equal In consequence the magnetic forces, or torques about-the pin I5, arising because of change in direction of the current paths entering and leaving the bridging member Il, as compared with the direction in number Il, are in opposition and neutralize each other. Specifically, with respect to pin IS the forces developed at the upper end of member Il tend to rotate it in a counterclockwise direction while those developed at the lower end tend to rotate it in a clockwise direction. The position of pivot pin I5, which is latched into fixed position, is preferably selected so that these forces balance, or so that they produce a bias upon member ll in a direction to increase the circuit-closing contact pressure between the surfaces Ila and Ilia. In general the pin I5 may be located about midway of surfaces Ila and Ill: though for the increased contact pressures it should be above the mid-position.

In this connection it should be observed all of the aforesaid forces act in directions to move pivot pin I5 to the left. In consequence even though the contact pressures are thereby increased, as soon as pivot pin I5 is unlatched or released from its rigid restraining means, these magnetic forces, of substantial strength and effect, materially assist in the acceleration of the bridging member to the open circuit position.

With the parts in their closed circuit positions, as illustrated, the circuit breaker may be tripped to open position manually or automatically .in response to flow of abnormal current. In the event of a short circuit, or of a rapidly rising current, the tripping time may be decreased by providing, in parallel with the circuit which energizes the tripping magnet, an inductive shunt 30 which, by means of a plurality of magnetizable laminations 3|, functions to increase the proportion of current flowing through current path 32 of bus bar assembly I3a, which is arranged to energize a magnetizable frame 33 of a tripping magnet to attract its pivoted armature 34. The armature by link 35 moves the latching member 2I to releasing position against the bias of spring 39.

The aforesaid inductive current-responsive tripping means is of the form disclosed and broadly claimed in my co-pending application for Letters Patent Serial No. 106,522 filed October 20, 1936, upon which has issued Letters Patent No. 2,092,592.

As fully described in my aforesaid applica-- tion, the armature 36 serves to trip the circuit.

breaker to open circuit position at a predetermined current value during steady current conditions or ata lower value during a rapidly rising current condition. To vary the setting of the current-responsive tripping means, the magnetizable frame 33 may be pivoted as at 35 so that by loosening a thumb-nut 31 the frame 33 may be moved to increase or decrease the air gap between it and associated armature 34. A pointer or index 33a. cooperates with scale 38 graduated in terms of current.

Whenever the armature 34 is operated against the bias of its associated spring 39 to release the latching member 2|, the springs 22, 23 and 28 act simultaneously to move the bridging member Il to its open circuit position. At the instant of latch release the aforesaid magnetic forces developed at opposite ends of the bridging member Il jointly urge it toward the left as viewed in Figs. 1 and 2. Since these forces in magnitude rapidly increase with rising current, they greater curr'ent magnitudes.

are effective to decrease the opening time for the The springs 28 almultaneously tend to rotate the bridging member Il in a clockwise direction and to move its lower end against the arresting means or abutment block 25 while the magnetic forces and the springs 22 and 23 move the bridging member as a whole to the left as viewed in the drawings and towards the open position. As soon as the surface 21 strikes surface 251:. the bridging member rotates at high speed in a counterclockwise direction about a center determined by the concave surfaces 25a and 21.

In order quickly to initiate an arc, extremely high initial acceleration is necessary. To this end initial acceleration, at very high rate, is largely produced by the heavy, powerful spring 22, which is pre-stressed or maintained under substantial compression though the circuit breaker be in the open position. Since the forceof spring 22 is largely depended upon for the high initial rate of acceleration, it is effective only during the first part of the opening movement of the bridging member. To this end arms 400 (Fig. 7) of a spider l0 secured to rod 2l by a nut U are acted upon by spring 22 until they pass through interleaving arms l2a of a plate l2 the latter then taking the stress of spring 22. Preferably the spring 22 is effective until all of the upper contact surfaces of bridgingmember Il are separated from their associated sur aces. During the remaining opening movement the lighter spring 23, of smaller diameter than the annular space between radial arms 42a, continues to press against the spider l0 to insure at high speed full opening movement of the circuit breaker. Due to the high speeds involved and the resultant magnitude of kinetic energy, it is desirable to decelerate the movable structure as the fully open position is attained, by means of an energy absorber and dissipater of a type later to be described.

During the initial opening movement of bridging member i l and as a result of separation of surfaces "la and Ila, the current is transferred to arcing contacts 43 and ll supported, respectively, by each of elements I6-I9 of the bridging member Il, and by stationary contact structure I0. The arcing contacts, formed of any suitable are resistant material, such as carbon, tungsten, molybdenum, or the like, by reason of the individual pivotal mountings lla and biasing springs l5 for each of contacts ll, engage each other an instant before and separate an instant after surfaces Illa and Ila and so relieve them from the duty of making and breaking the circuit. By reason of the pivotal mounting and the direction of current flow, magnetic forces act on arcing contact ll in directionto bias it towards the bridging member Il and therefore assists in accelerating it toward its circuit-opening position. These forces also insure maintenance of contact pressure between the arcing contacts until they separate from each other.

'' If, upon separation of arcing contacts l3 and ll,

turns to produce a strong magnetic field acting in a direction to hasten the above transfer, the lengthening and extinction of the arc.

As soon as the arc is transferred to the arcing horns 40 and 41 the bridging member i4 is effectively removed from the circuit since current may then flow from the stud l3, bus bar lla, stationary structure ii, supporting elements (not shown) common to and electrically connected to structure i i and arcing horn 46, by way of the arc to horn 41, blowout coil 48 and by bus bar in to the stud i 2. A fiexible conductor 49, Fig. 2, interconnects arcing contact 44, arcing horn 41 and the stationary contact structure i0 subtantially to eliminate flow of current by way of the pivotal mounting 44a--and of spring 45.

I have found that circuit breakers embodying my invention, and which have continuous current ratings of the order of 10,000 amperes at voltages of 600 or 1500 volts or more, will, when connected in a circuit capable of a current rise at the rate of 10,000,000 amperes per second, function to limit the current in a typical circuit, to values of around 50,000 amperes as against a possible rise of the current to about 250,000 amperes, a rise occurring with circuit breakers now available on the market.

The energy absorbing and dissipating means referred to above is preferably of the type described and claimed in co-pending application Serial No. 98,562, filed August 29, 1936, patented November 15, 1938, Patent it 2,137,001, by George A. Healis for Circuit breaker and energy absorber therefor and assigned to the same assignee as the presentinvention.

In brief, Figs. 2 and 9, the bridging elements l6-l9 may be provided with impact members 50, preferably of hardened steel, arranged to engage an inclined surface 5la of brake block 5i, itself provided with friction surfaces 53 and 54 along upper and lower horizontal surfaces thereof, and with a recess to receive one end of a spring 52. One end of a crank arm 55 is engaged by the other end of spring 52 while the opposite end of the crank arm bears against a brake shoe which cooperates with friction surface 53. As the impact members 50 engage the inclined surface 5ia, a component of force is effective to press the brake block 5! firmly against an upper surface of housing 51. As the block is displaced to the left, the spring 52 is compressed and applies through the crank arm 55 a rapidly increasing force upon the brake shoe and the friction surfaces 53 and 54. In this manner the kinetic energy of the moving parts is quickly absorbed and rapidly dissipated to prevent rebound of the bridging member i4 and to eliminate damaging shocks and hammer blows to the parts of the circuit breaker.

As shown in Fig. 2, the energy absorber may also include a spring 58, normally maintained under compression by the plate 42 secured to housing 51 by cap screws 42b, which acts as a final cushion or resilient stop for the brake block 5| as the limit of the circuit-opening move ment of the bridging member is approached. To this end a spring-seat 59 has an extension projecting through a wall of housing 51 and between arms 5511 and 55b of crank arms 55. As shown in Fig. 9, the block 5i may have a recess for receiving the projecting end of springseat 59.

After the circuit breaker has operated to its fully open position it may be reclosed by any suitable mechanism. when of the type shown in Fig. 1 it is necessary to reset the operating mechanism since it may remain stationary during circuit-opening movement of members i4 and 20. This is done by rotating, either manually or by the weight of the solenoid plunger, the crank arm or lever 60 in a counter-clockwise direction to break an operating toggle comprising the righthand portion of crank 60 and the link 6i. This allows spring 60a to move in a clockwise direction a lever 82, pivoted on the frame at 63, which by means of a link 64, pivoted to the lever 52 and to the pivot pin 2ia secured to the sliding plate 05, moves the latter to the left. The plate 55 is guided by pins 66 and ii! and cooperating slots which maintain it in alignment with the actuating member 20. As the right-hand edges of the slots approach'pins 6G and 61 the hook-shaped end of latch 2i engages catch 20a of member 20. The mechanism is now set for reclosing the circuit breaker.

Closure of the circuit breaker is accomplished, M

either manually, or electrically through solenoid S, by rotating crank arm in a clockwise direction to reset the toggle 60-6l. As that is done the lever 82, link 54, and the latching member 2i move the actuating member 20 to the right against the bias of the springs. The horizontal or longitudinal movement of member 20, guided by an elongated slot, receiving pin 66, and by the housing 51 through which slides the integral extension 24, rotates the bridging member in a clockwise direction about its lower center or axis of rotation. The lower contact surfaces l4b move into engagement with surfaces lib and the arcing contacts 43 engage contacts 44, further movement compressing the springs 45. At about this time the arms 40a of spider after moving between arms 42a of the fixed plate 02, engage the left end of the powerful pre-stressed spring 22. During the final circuit closing movement against the bias of springs 22, 23 and it, the contact surfaces I ia engage surfaces lilo which then act as a fulcrum, or determine a new axis of rotation for bridging member it. Thus the direction of rotation of bridging member i4 is reversed as the pin i5 continues its movement to the right. The resultant counter-clockwise rotation about surfaces Ma and llla separates the surfaces 27 and 2511, the springs iii"; then being effective to exert upon bridging member iii a substantial force whose vertical and horizontal components develop high circuit-closing pressures at the contact surfaces lilo, Hit: and l lb, i4b. During this final closing movement the contact surfaces lib and l4b slide over each other under increasing contact pressure, the resultant cleaning and wiping action insuring an electrical connection of minimum resistance. At the same time and by reason of the shape or angles of surfaces lib and i4?) a vertical movement of member i4 is produced which insures a like wiping and cleaning action between surfaces Illa and Ma which are at a substantial angle, about to the surfaces lib and Nb. Surfaces l4b may slide over surfaces lib because they are substantially tangential to the new radius of rotation defined by a straight line joining the centers of spaced surfaces I01: and lib, or extending from the point of contact of the upper surfaces la and Mo to the point or plane of contact between the lower surfaces lib and Hi). The angle between the aforesaid line and the plane surface Ilia is small as compared with the large, substantially 90, angle between that line and plane surface i lb.

In the event of an overload condition during closure of the circuit breaker, the tripping means is eifective at all times to move the armature 34 to release the actuating member 20 irrespective of, and without interference from, the crank arm 60. In short, the circuit breaker is at all times trip free of the operating or closing mechanism.

For a more complete understanding of additional structural features of the above described embodiment of my invention, reference may be had to Figs. 2-11, inclusive. As already explained, the plate-like bridging elements, preferably of copper, are relatively thin to maintain low their mass, and relatively wide to provide adequate strength and substantial heat-radiating surfaces. In addition, those portions of the elements above and to the right of line llm, Fig. 2, are thicker than the intermediate portions to provide for reception of silver inserts Ila of greater width than the central portions of the elements. The increased cross-section provides a more rapid iiow of heat from the contact surfaces to the massive heat-absorbing and dissipating stationary contact structure l and to the radiating surfaces of the elements. Similarly those portions of the elements iii-i9 below and to the left of diagonal line 1411, Fig. 2, are thicker or of increased cross-section. Besides the aforesaid features which produce lower temperatures at the contact surfaces, the increased cross-section provides a greater bearing surface for each element with respect to that of the arresting means, in this case comprising an adjustable abutment block 2517, which is of advantage to minimize deformation.

The respective ends of the bridging elements 16-19 are spaced from each other to provide for vertical ventilating passages between adjacent elements. This spacing is predetermined by the steel inserts l6a-l9a which, Figs. 3 and 4, bear against each other and against actuating member 20.

To prevent possible formation of arcs'between surfaces lib and Nb there may be provided flexible conductors 68, one, for each of bridging elements 16-!9 connected in parallel or in shunt circuit relation therewith. Corresponding ends of the conductors are by cap screws individually clamped to the bridging elements while the opposite ends are, by cap screws 6d, extending into threaded openingslll, clamped to abutment block 252).

To provide an equalizing connection by means of which the pressure of each of springs 28 may be applied to a pair of the bridging elements, each element within its thickened portion and adjacent its convex projection or surface 21, Fig. 2, is provided with reentrant openings, Figs. 5 and 6, or one counterbored from opposite sides to form therebetween a central ridge 12 whichmay be flat as shown in Fig. 5 or rounded as in Fig. 6 for line contact with cooperating pins 13 and 14. From the central portion of each pin and between adjacent bridging elements there extends a spacing and positioning flange 13a of greater diameter than the counterbored openings. A shorter pin 15, having a like positioning flange, interconnects elements 11 and 18. The bias of springs 28 may be applied to the bridging elements by means of rods 11 and 18 extending through counterbored openings 80 and 8| of the abutment block 251). The rods are identical in construction, and only one, the rod 11, will be described in detail.

As shown in Fig. 2, the outer end of rod 11 is threaded to receive adjusting nuts 19 which retain'the spring 28 under substantial compression. The bias of the spring, one end bearing against a. shoulder provided within counterbored opening iii of block 25b, and the other end against a washer adjacent nuts 19, tends to move rod 11 downwardly and along its axis. The inner, flattened end 110, of rod 11, however, has an opening which receives the positioning flange 1311 so that the bias of spring 28 is applied to, and by the pin 13 divided between, elements 16 and i1. besides lying in a plane which includes the centers of curved surfaces 250- and 21, is in direction to equalize the circuit-closing pressures between contact surfaces lib, Nb and- Illa, Ma.

To provide for misalignmen differences in dimensions, or positions, of the elements, there is sumcient clearance, Fig. 6, fora slight tilting of the pin 13 with respect to its ridge 13a, which does not affect the distribution of force but maintains the equality of its division between elements 16 and I1.. The permissible angular movement of pins 13 and 14 also prevents unequal wear of the lower contact surfaces from affecting the magnitude of the circuit-closing pressures thereon.

The result of wear of contact surfaces Illa and Ma is to produce about pin 15 clockwise displacement of bridging member: M from its original position, and decreased spacing, with the circuit breaker in closed circuit position, between complementary surfaces 25a and 21. To compensate therefor, the abutment block 25?) may be moved to the left. For this purpose there are provided bolts 82, enlarged heads 82a (Fig. 11) of which extend between projections 84 (Fig. 8) of block 25b, and the threaded ends of which extend through threaded openings of housing 51. By loosening locknuts 85 of each of bolts 82 as well as clamping bolts 86, extending through .horizontally elongated openings of stationary structure I i into threaded engagement with block 251), the bolts 82 may be rotated to move the block 2512 to the left. It is then rigidly clamped into position by carrying out the foregoing steps in reverse order.

Instead of adjusting the abutment block 25b, which may be rigid as shown in Fig. l, the upper contact structure it may be moved to the left, clamping screws or bolts 81 first being loosened and adjusting screws 88 then operated to procure the necessary adjustment. Since inthe closed circuit position a clearance of only one-sixteenth of an inch need be provided between surfaces 25a and 21, the extent of the required movement of structure Ill is of corresponding magnitude.

For brevity, corresponding parts of the mothfled form of my invention, Figs. 12-14, have the same reference characters as the above-described modification of my invention.

Referring to Figs. 12 and 13, the bridging elements is and 11, shown as comprising the bridging member it, are by their respective bushings 5a and i111. mounted upon a pin l5 supported at its opposite ends from an actuating member 90, itself pivoted upon a stationary pin 9! carried by the frame (not shown). The spaced sides of the actuating member 90 are interconnected by a rigid L-shaped cross-member 90a, for clarity omitted in Fig. 13. The bushings i6a and Na, as in the prior modification, are provided with vertically elongated openings, Fig. 10, which permit the bridging member 14- to move down- The line of action of each of springs 28,

wardly to take care of wear between the lower, horizontally disposed, contact surfaces Ilb and Ilb. The actuating member may be rotated about its pivot 9| by means of any suitable mechanism though preferably of the type generically illustrated in Fig. 1. For this purpose an operating member 92 is pivotally connected at 93 to the actuating member 9 0. By moving either manually or automatically the operating member 92 downwardly, as viewed in Fig. 12, the bridging member I4 is moved to the open circuit position.

During circuit-closing operation, the operating member 92 is moved upwardly, rotating the actuating member 99 in a clockwise direction. As described in connection with the modification of Figs. 1-11, the arcing contacts first engage, followed by engagement of the vertically disposed contact surfaces lfla and 14a. Additional c1ockwise movement of actuating member 99 produces counterclockwise rotation of the bridging member l4 about an axis located at the upper end of the bridging member, the lower contact surfaces |4b sliding over surfaces III) to produce a cleaning and wiping action and todevelop circult-closing pressures upon all contact surfaces. In the closed circuit position the pin I5 is rigidly locked into a fixed position to insure, as explained above. the equalization of magnetic forces developed at the opposite ends of the bridging member.

The contact pressures in this instance are developed-by means of a plurality of springs, one for each bridging element. As shown, the springs 94 and 95 are mounted, respectively, between opposite sides of U-shaped links 96 and 91, each cross-portion of which is provided with a spring seat. With the circuit breaker in the open circuit position, the springs 94 and 95 acting upon the links and upon lugs 98 and 99 maintain the bridging member l4 in a position adjacent a pin I09 which interconnects the sides of the actuating member 90, the lugs 98 and 99 formed integrally with actuating member 99 and extending from cross-member 99a, and the links 96 and 91. The links are provided with elongated slots 96a and 91a which permit the aforesaid movement of the bridging member l4 towards pin I09, individual pins [0| and J2 interconnecting the lower ends of bridging elements l6 and I! with the respective ends of links 96 and 91.

Reverting to the circuit-closing operation, after engagement of surfaces Illa and 1 4a the continuing clockwise movement of actuating member rotates the lower end of the bridging member H in a counter-clockwise direction against the bias of the springs 94 and which are preferably under initial stress or compression, as explained above for corresponding springs 28, and high circuit-closing pressures are developed upon all contact surfaces.

In accord with this modification the links 96 and 91 perform the functions of the arresting means or abutment 25a of Figs. 1-11; particularly insofar as the slots 99a and 91a limit the extent of relative movement between the bridging and actuating members.

Though the stationary contact structure I9 may be adjusted to the right or left to compensate for contact wear, as described in connection with Fig. 2, I prefer to adjust the relation of the operating member 92 with respect to the actuating member 90 to provide the necessary compensation. This may be readily done by providing a threaded connection between the operating ing member,

member 92 and a clamp I94 provided with a clamping bolt I05. By loosening the bolt IIII the operating member 92 may be unscrewed a few turns to lengthen the distance between pin 93 and the opposite end (not shown) of member 92. In consequence, for the same extent of circuit-closing, movement of member 92 there will be produced greater movement of the bridging member i 4 to the right as viewed in Fig. 12, which will, of course, produce somewhat greater compression of springs 94 and 95, or in case of wear of contacts 10a and 14a insure the relative movement, between surfaces llb and 14b and between the lower end of the bridging member and the actuating member 90, necessary to render eil'ective the bias of springs 94 and 95 to produce the circuit-closing contact pressures.

Since in this modification the bridging elements l6 and 11 are by pin I5, links 96 and 91, and pin I00 supported by and interconnected with the actuating member 90, the bridging member as a whole and including springs 94 and 95 and other associated parts may be removed and replaced as a unit, a feature of assembly'which is of advantage both in the field and in the factory.

While I have shown particular embodiments of my invention, it will be understood that I do not limit myself thereto since many modifications may be made, and I therefore contemplate by the appended claims to cover any such modifications as fall within the spirit and scope of my invention. a

I claim:

1. A circuit interrupter comprising spaced contact structures, a rigid bridging member therefor, actuating means movable in a single direction for rotating said bridging member about a pivotal axis adjacent one end thereof to bring its opposite end into contact engagement with one of said structures, and for thereafter rotating said member in the opposite direction to move said first-named end of said bridging member to produce a wiping action between it and said other structure.

2. A circuit interrupter comprising spaced contact structures, a rigid bridging member therefor one end of which is disposed for engagement with one of said structures, means for rotating the opposite end of said bridging member, about a pivotal axis adjacent said one end, into contact engagement with the other of said structures, and for thereafter rotating said member about an axis adjacent said opposite end to slide said one end over said other structure, and resilient means operable by said sliding movement to produce circuit-closing contact pressures between said bridging member and each of said structures.

3. A circuit interrupter comprising spaced contact structures, a rigid bridging member therefor, an abutment adjacent one end of said member, means for rotating the opposite end of said bridgabout a pivotal axis adjacent said abutment, into contact engagement with one structure, and for thereafter sliding in wiping contact engagement with said other structure the end of said bridging member adjacent said abutment, and resilient means operable by said sliding movement for producing circuit-closing contact pressures between said bridging member and both of said structures.

4. A circuit interrupter comprising spaced contact structures, a rigid bridging member disposed for abutting contact engagement with both of said structures, a spring, operatively connected to said member intermediate its ends, for biasing it to a circuit-opening position, releasable means restraining said member in circuit-closing position, said spring upon release of said restraining means bodily moving said member towards said circuit-opening position, means operable after initiation of said movement for arresting movementof one end of said member, the opposite end continuing its movement to said circuit-opening position, and means biasing said one end of said member at all times towards said arresting means.

5. A circuit interrupter comprising spaced contact structures, a rigid bridging member the opposite ends of which, in the closed circuit position of the interrupter, engage said structures, biasing means, operatively connected to said member intermediate its ends, comprising a powerful spring for initiating movement of said member at high speed towards a circuit-opening position, and a. second spring effective during the entire circuit-opening movement of said member for maintaining high its speed of movement, releasable means restraining said member in said closed circuit position, said powerful spring upon release of said restraining means bodily moving at high speed'said member towards said circuitopening position, and rigid means for arresting movement of one end of said member to produce high speed pivotal movement of the opposite end of said member to said circuit-opening position.

6. A circuit interrupter comprising spaced contact structures, a rigid bridging member the opposite ends of which, in the closed circuit position of the interrupter, engage said structures, a powerful biasing means operable through a short distance for producing a high rate of acceleration of said bridging member towards open circuit position, a second biasing means of less power for maintaining high said speed of 'movement, releasable means restraining said member in said closed circuit position, said powerful biasing means upon release of said restraining means bodily moving at high speed said member towards said circuit-opening position, and means for arresting movement of one end of said member to produce high speed pivotal movement of the opposite end of said member to said circuit-opening position, said arresting means determining the axis of rotation of said member, and a spring for biasing said bridging member toward said axis.

7. A circuit breaker comprising spaced contact structures, a rigid bridging member having spaced contact surfaces disposed in planes generally normal to each other for abutting engagement with said structures, an operating member connected to said bridging member intermediate said contact surfaces for rotating one end of said bridging member, about an axis adjacent the opposite end thereof, into and out of circuit-closing position, and resilient means responsive to limited pivotal movement of said member about said one end for producing circuit-closing pressures upon all of said contact surfaces.

8. A circuit interrupter comprising spaced contact structures, a bridging member having spaced contact surfaces for engaging said structures, corresponding surfaces of said member and one of said structures lying in a plane generally tangential to a line extending therefrom to the point of engagement of said other surfaces, and means i? operating said member first into engagement with said structures and then to slide said tangentially disposed surfaces relative to each other for.

wiping contact engagement,

9. Acircuit interruptercomprising spaced contact structures each having a contact surface disposed generally at right angles to a corresponding surface of the other structure, a bridging member having contact surfaces respectively disposed generally at right angles to each other for abutting engagement with said surfaces of said structures, and means connected to said bridging member intermediate said surfaces and operable by sliding movement between said surfaces to produce circuit-closing pressures upon said surfaces.

'10. A circuit interrupter comprising a bridging member having spaced contact surfaces disposed at substantial angles to each other, stationary contact structures having contact surfaces engageable by those of said member, rigid means pivotally connected to said member intermediate said surfaces and operable through a predetermined distance to engage and disengage said surfaces, and means for Varying the relative positions of said member and said structures to produce engagement of said surfaces for different predetermined movement of said rigid means.

11. In a circuit interrupter, a briding element comprising a thin plate-like member having end portions of greater cross-sectional area than the intermediate portion thereof, and two contact -'members, one supported by one of said end portions in a plane at a substantial angle to that of the other contact member supported at the other of said end portions.

'12. In a circuit interrupter, -a plate-like bridg ing element having thickened end-portions, con

tact members of greater width than the intermediate portion of said element, means securin one of said contact members to one end of said element, and means securing the other of said contact members edgewise of and with its contact face parallel to a side of said element and within one of said thickened end portions.

13. In a circuit interrupter, a rigid plate-like bridging element having thickened edges at one end and along one side thereof, contact members supported by said thickened edges at opposite ends of said element, and actuating means connected to said element intermediate said contact members.

14. In a circuit interrupter, a plurality of platelike bridging elements each having enlarged portions adjacent one end and along an opposite edge thereof, a contact member supported by each of said enlarged portions and at right angles to each other, each of said elements having adjacent said one end thereof a portion forming a bearing surface, means interconnecting said elements, and a bearing surface coextensive with all of said bearing surfaces of said elements, and means for rotating said elements about said bearing surfaces.

15. A circuit interrupter comprising spaced contact structures, a bridging member having contact surfaces respectively disposed in planes generally at right angles to each other for circuit-closing engagement with said structures, conductors extending in the same direction to and from said structures, whereby magnetic forces incident to current flow tend to move said mem. her away from said structures, and means rigidly supporting said member for rotation about an axis intermediate its contact surfaces to neutralize said forces.

16. A circuit interrupter comprising spaced contact structures, a rigid bridging member in circuit-closing position having spaced contact surfaces abutting against rigid contact surfaces of said structures, operating means pivotally engaging said member intermediate said surfaces to restrain it in circuit-closing position, conductors from said structures so disposed with respect to said bridging member while engaging said spaced contact structures that magnetic forces incident to current flow therethrough produce oppositely disposed torques on said member about its pivotal axis and tend bodily to move said memher away from said structures, said pivotal axis being so disposed in said member as to neutralize said torques produced by said forces, and means for releasing said operating means to render effective said forces for simultaneous movement of said surfaces toward a circuit-opening position, and resilient means for biasing said bridging member to said circuit-opening position.

1'7. A circuit breaker comprising spaced contact structures, an actuating member, a rigid bridging member pivoted intermediate its ends to, and supported by, said actuating member, said bridging member and said structures having cooperating contact surfaces disposed adjacent the respective ends of said bridging member, said contact surfaces adjacent one end thereof, when said bridging member occupies its closedcircuit position, lying in a plane at a substantial angle to the plane of said contact surfaces adjacent said other end, and means including saidactuating member for moving said bridging member into and out of said closed circuit position.

18. A circuit interrupter comprising spaced contact structures, a rigid bridging member therefor, means for rotating one end of said bridging member, about a pivotal axis adjacent its opposite end, into contact engagement with one structure, and for thereafter sliding said opposite end of said bridging member over said other structure, a guide member connected to said opposite end of said bridging member and extending diagonally away from said contact structures, and resilient means operable by said sliding movement to apply through said guide member circuit-closing contact pressures between said bridging member and each of said structures.

19. A circuit interrupter comprising spaced contact structures, a rigid bridging member therefor normally engaging one of said structures, a block forming an abutment adjacent one end of said member, means for rotating said member about said abutment block to move the opposite end of said member into engagement with the other of said structures, a rod connected at one end to said member, said block having an opening through which said rod extends, a spring encircling said rod for biasing said member into said normal engagement with said one structure and toward said block, and said rotating means after engagement of said structures by said bridging member sliding said one end of said member away from said block to stress said spring and thereby develop substantial circuit-closing contact pressures.

20. A circuit interrupter comprising spaced contact structures, a rigid bridging member therefor, a spring for biasing said bridging member from a closed to an open circuit position, an actuating member connected to the central portion of said bridging member for rotating one end of said member, about a pivotal axis adjacent its opposite end, into abutting engagement with one structure, and for thereafter sliding said opposite end of said bridging member over said other structure, resilient means operable by said sliding movement to produce substantial circuit-closing contact pressures between said bridging member and each of said structures, and releasable means normally restraining said bridging member in circuit-closing position and operable in response to a predetermined current condition in the circuit interrupter to release said bridging member for operation by said spring and said resilient means to said open circuit position.

21. A circuit interrupter comprising spaced contact structures, one having a contact surface disposed in a horizontal plane and the other having a contact surface disposed in a vertical plane, a bridging member having vertical and horizontal contact surfaces in the circuit-closing position of the interrupter engaging those of said structures, resilient means connected to said bridging member to bias said horizontally disposed surfaces into engagement and having its line of action such as to oppose sliding movement between said horizontal contact surfaces and to produce substantial circuit-closing pressures between all of said surfaces, and means operatively engaging said bridging member for producing said sliding movement and said circuit-closing pressures.

22. A 'circuit interrupter comprising spaced contact structures, a plate-like bridging member, one end of which rests upon a first of said structures and the opposite end, in circuit-closing position, disposed into edgewise engagement with the second of said structures, actuating means connected to said bridging member intermediate its ends for rotating it, first about an axis adjacent one end and then about an axis adjacent its opposite end, from an open to said circuit-closing position, and resilient means operable by pivotal movement of said member about said secondnamed axis for producing substantial circuitclosing pressures between said bridging member and said structures.

23. A circuit interrupter comprising spaced contact structures having contact surfaces disposed, respectively, in planes generally at right angles to each other, a rigid bridging member having contact surfaces at opposite end portions for engaging said surfaces of said structures, biasing means extending from one side of, and connected to, an intermediate portion of said member for producing high speed operation thereof from a closed to a circuit-opening position, actuating means connected to, and extending from the other side of, said intermediate portion, releasable means normally engaging said actuating means to restrain said member in said closed circuit position and operable to release said member for operation to said circuit-opening position, and biasing means connected to said member adjacent one end thereof for pressing said surfaces of said bridging member against said surfaces of said structures.

24. A circuit interrupter comprising spaced contact structures having contact surfaces disposed, respectively, in planes generally normal to each other, a rigid plate-like bridging member having contact surfaces at opposite end portions for edgewise engagement with said surfaces of said structures, biasing means extending from one side of, and connected to, an intermediate portion of said member for producing high speed operation thereof from a closed to an open circuit position, actuating means connected to, and extending from the other side of, said intermediate portion, an abutment adjacent one end of said member, means normally restraining said member in a circuit-closing position and with said one end thereof spaced from said abutment, resilient means connected to said member adjacent one end thereof for producing circuit-closing pressures upon all of said contactsurfaces, means for operating said restraining means to release for movement, by said biasing means, one end of said member into engagement with said abutmentand for rotation of the other end to said open circuit position.

25. li circuit interrupter comprising spaced contact structures, a rigid bridging member therefor one end of -which engages one of said structures, means operable in one direction for rotating the other end of said bridging member,

about a pivotal axis adjacent said one end, into abutting engagement with the other of said structamed under substantial compression, means engaging said second spring in circuit-closing position of the interrupter for biasing said memher to a circuit-opening position, means for restraining said bridging member in said circuitclosing position, said second spring upon release of said restraining means producing a very high rate of acceleration of said bridging member toward said circuit-opening position, and means operable after a predetermined-opening movement for removing from said bridging member the bias of said second spring.

26. A circuit interrupter comprising spaced contact structures, a rigid bridging member therefor comprising a plurality of substantially duplicate plate-like elements the corresponding ends of which normally engage one of said structures, a block forming an abutment ior said corresponding ends of said elements, means for rotating said member about said abutment block to move the opposite end-portions of said elements into engagement with the other of said structures, said block having openings, in number equal to the number of pairs of said elements, a rod for each opening having a narrow, fiat, end portion nesting between each pair of said elements, 9. pin interconnecting each pair oi said elements, each pin having a flange extending between its associated pair of elements and engaged by said flat end of said rod, biasing means con nected to said rods, for biasing said elements toward said one structure and toward said block, and said rotating means after engagement of said structures by said elements sliding against the bias of said biasing means said corresponding ends of said elements away from said block and in wiping. contact-engagement with said one structure to develop substantial circuit-closing contact pressures between each of said elements and each of said structures.

27. In a circuit interrupter, a bridging member compr sing a plurality of plate-like bridging elements, means interconnecting and spacing said elements apart one from the other to provide ventilating passages therebetween, said elements having aligned and reentrant openings at adjacent corresponding ends thereof to form central flanges individual to and coinciding with the longitudinal axes of said elements, a pn, opposite ends of which engage the flanges of an adjacent pair of said elements, and a flange carried by each of said pins of diameter greater than that of said reentrant portions disposed between its associated pair of elements.

28. A circuit interrupter comprising spaced contact structures, a bridging member, one end portion resting upon and in contact engagement with one of said structures and the opposite end portion engaging the other of said structures in a plane at a substantial angle to the plane of said contact engagement of said one end portion, actuating means pivoted to said bridging member about midway of said structures, and resilient means operable by sliding movement of said one end portion over its associated structure for producing equalized circuit-closing pressures upon said end portions of said bridging member.

29. A circuit interrupter comprising spaced contact structures, a bridging member having at opposite end portions contact surfaces disposed for abutting contact engagement with said structures, an actuating member, and means intermediate oi, and disposed substantially on a line extending from one contact surface to the other for pivotally interconnecting said bridging and.

actuating members.

30. A circuit interrupter comprising spaced contact structures having rigid contact surfaces, a pair of bridging elements in circuit-closing position engaging said surfaces, resilient means 1 biasing said elements to a circuit-opening position, actuating means for moving said elements against the bias of said resilient means to said circuit-closing position, a member engaging each of said elements, and a spring connected to said member and operable by said actuating means to apply through said member circuit-closing pressures upon all of said contact surfaces.

321. A circuit interrupter comprising spaced contact structures, a rigid bridging member therefor, an actuating member pivotally connected to said bridging member intermediate its ends, a pivot for said actuating member disposed adjacent one end of said bridging member, arresting means for said one end of said bridging member comprising a link interconnecting, and forming a lost-motion connection between, said bridging and actuating members, and resilient means operable by movement of said bridging member away from said actuating member for developing circuit-closing pressures between said bridging member and both of said contact structures.

32. A circuit interrupter comprising a pair of spaced, rigid contact structures, a rigid bridging member having contact surfaces respectively disposed in planes at right angles to each other for circuit-closingengagement with said structure, conductors extending in the same direction to and from said structures, whereby magnetic forces incident to current flow tend to move said member away from said structures, pivoted means normally rigidly supporting said member along an axis intermediate its contact surfaces, and resilient means biasing said member about said axis in direction to produce pressure engagement with both of said structures, said axis being located in said member in a position such that said magnetic forces tend to increase said engaging pressure.

33. In a circuit interrupter, spaced contact structures having rigid contact surfaces, a rigid bridging member for engaging said surfaces, opcrating means for moving said bridging member into and out of engagement with said surfaces, a pivoted connection between said member and said operating means, rigid retaining means for releasably holding said pivoted connection in fixed position, and resilient means for producing circuit-closing contact pressures at said surfaces.

34. In a circuit interrupter, spaced contact structures having rigid contact surfaces, a'rigid bridging member for engaging said surfaces, op-- erating means for moving said bridging member into and out of engagement with said surfaces, 9. pivoted connection between said member and said operating means, rigid retaining means for releasably holding said pivoted connection in fixed position, resilient means for producing circuitclosing contact pressures at said surfaces, and means for adjusting the relative positions of said pivoted connection and of said contact surfaces of said spaced structures to vary said contact pressures.

35. A circuit interrupter comprising spaced contact structures each having a rigid contact surface, a rigid bridging member, an actuating member pivotally connected to said bridging member, operating means for moving said actuating member to move into engagement said surfaces of said bridging member and of said structures, corresponding surfaces lying generally tangential to a line extending thereto from said other spaced surfaces, said operating means after engagement of said surfaces rotating said bridging member to slide one of said tangential sur faces over the other, and resilient means operable by said sliding movement for producing circuitclosing contact pressures between all of said contact surfaces.

36. Ina circuit interrupter, a first rigid contact structure having a rigid contact surface, a second rigid contact structure spaced from said first structure and having a rigid contact surface, a rigid bridging member having complementary contact surfaces for engaging said surfaces of said structures, operating means for moving said bridging member into and out of engagement with said structures, a pivotal connection between said member and said operating means whereby actuation of said operating means toward contact engaging position rotates said member first about a center adjacent said first structure and subsequently about a center adjacent said second structure, rigid retaining means contact engaging position, resilient means for producing current-carrying contact pressures at said surfaces, resilient contact means supported by the second of said structures and initially engaging said member before engagement of said member and said second structure, and a current path through said resilient contact means for producing magnetic forces effective to increase its circuit-closing contact pressure during current fiow therethrough.

37. A circuit interrupter comprising spaced contact structures, said structures having rigid contact surfaces generally at right angles to each other, a rigid bridging element having corresponding contact surfaces for engagement with the surfaces of said structures when in circuitclosing position, an actuating member movable in a fixed path and effective to move said bridgother for abutting engagement, in circuit-closing position, with said surfaces of said structures, an actuating member movable in a fixed path for moving said bridging element into and out of engagement with the surfaces of said structures, means connecting together said element and said member and providing for additional movement of said element in a direction normal to one of said surfaces comprising a pin disposed within an opening elongated in a direction normal to said one of said surfaces, and resilient means biasing said element toward said one surface.

WILLIAM M. SCOTT, JR. 

